1. Field of the Invention
This invention relates to apparatus for opening containers with twist-off tops, and, more particularly, to appliances for opening such containers held between a stationary platen and a rotating platen of the appliance.
2. Background Information
Conventional apparatus for opening jars and bottles generally consists of hand-held devices providing means to aid the user in gripping the edge of the top of the jar or bottle so that the top can be twisted off. However, since this type of device does not assist in holding the jar itself, excluding the top, often the jar itself cannot be held without slipping when an attempt is made to remove the top. Also, the normal forces necessary to provide sufficient torque to twist a stuck lid may be enough to crush the top. Furthermore, since the tops of jars and bottles vary greatly in diameter, it is difficult to configure a device of this type to handle a sufficient variation in types of containers, and the user is required to reset the device between its use on different types of jars and bottles.
An example of this type of device is found in U.S. Pat. No. 5,365,806, which describes a three-in-one mechanical remover for bottle caps, bottle corks, and jar caps of various sizes. The device includes a vice system along a hand-held vertical post, with a moving toothed rubber vice grip being manually driven with a vice screw along the vertical post. The jar top is gripped between the moving toothed rubber vice grip and a stationary rubber vice grip extending outward from the opposite end of the vertical post.
Other examples of the patent literature describe counter top or wall-mounted appliances which overcome some of the disadvantages of hand-held devices, including the danger of having a glass container break from overstressing while it is being manually held. For example, U.S. Pat. No. 5,203,236, describes a wall-mounted lid-starter having a pair of belts, respectively enclosing a lid and a container for starting an overtightened lid from the container. A first end of the lid belt is spring biased to cooperate with a motor coupled to pull the belt second end in applying torque to the lid. Rotatable arms facilitate receiving the lid and container within the belts. The belts have sufficient stiffness to define receiving loops. In use, a container is inserted upwards into these loops until the container lid depresses a starter button mounted in a protruding housing shelf, causing the belts to be automatically pulled about the lid and container with the aid of pulling mechanisms, such as electric motors, within the housing.
While the appliance described above appears to be quite effective in loosening the lids of similar jars, what is needed is a method which is quickly adaptable for loosening the tops or lids of a number of different types of containers. Furthermore, to speed the process of opening containers, what is needed is an appliance which can begin the process of unscrewing a lid without first performing a separate step of tightening belts.
U.S. Pat. No. 5,647,251 describes a fully automatic jar opener having substantially horizontal clamps automatically movable along a horizontal plane between an open position and a jar clamping position. The clamps, while in a jar clamping position, hold a jar substantially without slippage, and a top jar retainer holds the cap substantially without slippage when the cap is subjected to a twisting force. A vertical drive automatically adjusts the relative vertical positions between the bottom and top retainers to apply a holding force on the cap. The automatic jar opener includes at least one motor for applying the twisting force to the top retainer, for moving the clamps along the horizontal plane, and for adjusting the relative vertical position between the retainers. A controller automatically controls the motor and enables loosening of the cap with one single, discrete user command.
U.S. Pat. No. 5,271,296 describes an automated cap remover and method for cap removal including a drive for causing relative rotation to occur between a container cap and a cap engaging unit. The drive brings the cap engaging unit into engagement with the cap and then slips to permit the cap to be unscrewed from the container. A control unit senses the torque created by the relative motion between the cap and the cap engaging unit, and when a drop in torque is sensed, the control unit causes the drive to move the cap and cap engaging unit out of engagement.
The jar opener of U.S. Pat. No. 5,647,251 thus requires three separate mechanical drives, while the automated cap remover of U.S. Pat. No. 5,271,296 requires two separate drives, including a slip clutch allowing vertical movement of the cap opposite the direction in which it is engaged as unscrewing takes place. What is needed is an appliance performing the jar opening function with a single mechanical drive.